Looks like it was made to serve as the bass driver in a 3-way speaker. It might be OK in that use, but it wouldn't dig very deep as a dedicated sub.
I was actually thinking that, too, Shady. They talked about it being great for 2-ways in their writeup... but as TLS mentioned, the woofer cutoff isn't nearly high enough...
Then, considering the sensitivity (<84dB!) and the D4 VCs, you could series-parallel a pair of these drivers to help boost your output while still keeping the cabinet size pretty reasonable. (Paired with a good mid, it
could be made to work.)
But the problem for these Epiques is, quite simply, there are better drivers out there for pretty much any job you would use these for. *shrugs